Boiler construction



March 31, 1936. R N- 2,035,605

BOILER CONSTRUCTION Y Filed Aug. 5, 1935 2 Sheets-Sheet l 7 4 6 j mi?Fez-'07 Jackson March 31, 1936. P. JACKSON BOILER CONSTRUCTION FiledAug. 5, 1935 2 Sheets-Sheet 2 3mm F91": Jac'k'an Patented Mar. 31, 1936U l'lE ill:- STATS PATENT OFFIQE BOILER CONSTRUCTION tion of KentuckyApplication August 5, 1935, Serial No. 34,825

7 Claims.

This invention relates to improvements in boiler construction.

It has-for its general object the provision of a boiler having front andrear tube supporting heads so constructed as to be self-supportingwithout necessitating the employment of the customary internal bracingmembers either above or below the tube sheets. The elimination of suchbraces avoids the presence of obstructions in the water and steam spacesof the boiler and makes these spaces much more accessible for cleaning.

Another object of the invention is to provide front and rear heads, thetube sheet portions of which are flat and parallel whereby all the tubesare of the same length. This is an obvious advantage to the boilermanufacturer from the standpoint of cheapness and ease of manufacture,and all of the tubes are subject to the same longitudinal expansion andcontraction under varying heat conditions, being thus relieved fromdifferential strains. Furthermore, the fact that the tube sheet portionsof the heads are flat and per-- pendicular to the tubes requires onlythat the tube sheets being perforated for receiving the tube ends anddispenses with the expensive necessity of providing seats in the tubesheets for the ends of the tubes.

Another object of the invention is the provision of a boiler head ofgeneral dished shape having a peripheral portion of spherical contour, aflat tube sheet area merging laterally directly into said sphericalperipheral portion, the peripheral portion being extended to meet andmerge with the lower boundary of the tube sheet portion, excepting wheremodified as will appear, to provide a manhole, the vertical geometricalelements of the underlying spherical portion being rotund andconstituting said underlying portion an eificient and adequatecompression member for supporting the tube sheets, the head being formedwith an upper portion intermediate the spherical periphery and the upperboundary of the tube sheet, merging into the latter and into the contourof the spherical peripheral portion above it,

' said upper intermediate portion being transvers ly very slightlycurved so that it may be correctly described as being substantiallyfiat, and having the curvature of those geometrical elements which liein vertical planes, approximately flat, making the upper intermediateportion as an optimum tension member for suspending the tube sheets andthe weight of the tubes.

Still another object of the invention is the provision of a manhole inthe boiler head beneath the tube sheet portion formed in a reentrantspherical depression in the outwardly convex lower portion of said head,the spherical contour of the boiler head in said depression affordingthe best shape for resisting deformation or collapse adjacent the edgeof said manhole.

Still another object of the invention is to provide a boiler havingdished heads, the peripheral margins of which merge smoothly with the cylindrical walls of said boiler.

Another object of the invention is to provide a boiler with heads of thetype described joined thereto by welding whereby a smooth surface isprovided on the inside of the boiler to facilitate cleaning.

Other objects of the invention will appear as the following descriptionof preferred and practical embodiments thereof proceeds.

In the drawings which accompany and form a part of the followingspecification and throughout the several figures of which the samecharacters of reference have been employed to designate identical parts:

Figure 1 is a perspective view of a boiler illustrating a head embodyingthe principles of the present invention;

Figure 2 is an end view of the same;

Figure 3 is a longitudinal section through the boiler showing bothheads, the intermediate part being broken away;

Figures 4, 5, 6 and 7 are vertical sections taken along correspondingsection lines indicated in Figure 1;

Figure 8 is a horizontal section taken along the line 8-8 of Figure 2;and

Figure 9 is a section taken along the line 9-4! of Figure 2.

Referring now in detail to the several figures the numeral I representsa boiler which is here shown as being cylindrical having at the oppositeends heads 2 and 3, it being understood that since the inventionconcerns itself primarily with the construction of the head, it isimmaterial Whether both heads of the boiler be alike or whether only onehead embody the present inventive concept providing, in those conceptsof the invention which envision the advantages of having the tubes ofequal length, that the opposite end of the boiler provide a fiat tubesheet parallel with the tube sheet portion of the head which embodiesthe features of the present invention.

The head 2 is of general dished shape, outwardly convex and having itsperipheral margin 4 preferably merging smoothly with the cylindricalwall of the boiler and being preferably buttwelded thereto as at 5 toprovide a smooth inte rior surface for the boiler shell. The peripheralcurvature of the head adjacent the margin 4 is spherical as indicated at6 and l. The vertical sections illustrated in Figures 4, 5, 6 and '7show that at the lower part of the head the spherical portion 1 extendsoutwardly and upwardly merging into the fiat tube sheet portion 8, thelatter being preferably, although not necessarily, in a vertical plane.The tube sheet portion 8 as will be observed particularly in Figure 2extends. preferably from a point above the horizontal diameter of thehead to a point a greater distance below said horizontal diameter,defining a steam chamber 9 in the upper part of the boiler. The tubesheet portion being fiat, it is merely necessary to perforate it for thereception of the tube ID, the latter intersecting it perpendicularly andbeing preferably welded thereto. It is not necessary to form the tubesheet portion with depressions or seats for fairly receiving the tubeends as would be required providing the tubes metthe tube sheet portionin any other than a perpendicular relation. Since it is contemplatedthat the opposite end of the boiler will be provided either with asimilar head or with a head providing a fiat tube sheet parallel to thetube sheet 8, the tubes l0 will all be of the same degree of expansionor contraction under equal heat conditions so that no differentialstrain is put upon the tubes or upon the boiler head itself. Thevertical geo-- metrical elements of the underlying spherical portion Iare of the very best shape to constitute the underlying sphericalportion a compression member for upholding the weight of the tube sheetportions and tubes themselves.

The portion ll of the boiler head immediately above the tube sheetportion 8 is very slightly curved transversely so that it may be said tobe substantially fiat, as is indicated in Figure 1 and Figures 4 to '7,inclusive, and the geometrical elements of said portion which lie invertical planes are of such flat curvature as to be approximatelyrectilinear, constituting the portion I! a tension member of optimumshape to suspend and sus tain the weight of the tube sheet portions andtubes.

A manhole I2 is provided in the spherical portion of the head whichunderlies the tube sheet portion, said manhole being formed in areentrant spherical depression 13 in the wall of said boiler head whichspherical depression has the best possible shape to prevent distortionor collapse under the pressure generated within the boiler.Consequently, the edge M of the manhole which is a source of weakness inmost boiler heads and has to be internally braced is thus madeadequately strong and self-sustaining.

By the above construction a boiler head is provided which isself-supporting against thermal as well as hydrostatic or fluid pressurestrains, thus enabling the manufacturer to dispense with the customaryinternal bracing, not only making an efiicient and stronger boiler, butleaving the water and steam spaces free from obstructions so that itcanbe easily and completely cleaned through the access afforded by themanhole l2.

While I have in the above description defined what I believe to be apreferred and practical embodiment of the invention, it will beunderstood that the specific details of construction as shown anddescribed are merely by way of example and not to be construed aslimiting the scope of the invention as defined in the appended claims.

What I claim is:

1. Boiler comprising a shell having front and rear heads at least one ofthe heads being dished and having a flat tube sheet portion'and aspherical marginal portion, the fiat tube sheet portion merging into thespherical marginal per-- tion laterally and below, said head having 2311 intermediate portion above said tube sheet por-' tion between thelatter and the upper spherical marginal portion, said intermediateportion being substantially fiat in a transverse direction and ofapproximately fiat curvature in vertical planes said substantially flatportion being inclined at, an acute angle to the plane of the tube sheetfor tensionally supporting the weight of said tube sheet portion andtubes, the opposite head having a fiat tube sheet parallel to the tubesheet portion of the other head, and tubes of equal length bridging thetube sheets.

2. Boiler comprising a curved shell having front and rear heads, atleast one of the heads being dished and having a flat tube sheet portionand spherical marginal portion, the flat tube sheet portion merging intothe spherical-margin-- al portion laterally and below, said headhavingan intermediate portion above said tube sheet portion and betweenthe latter and the upper spherical marginal portion, said intermediateportion being substantially flat in a transverse direction and ofapproximately fiat curvature in vertical planes said substantially fiatportion being inclined at an acute angle to the plane of the tube sheetfor tensionally supporting the tube sheet portion and weight of thetubes, the opposite head having a flat tube sheet parallel to the tubesheet portion of the other head, and tubes of equal length bridging thetube sheets, the marginal portion of said head conforming to thecurvature of said shell and registering with the end edges of saidshell.

3. Boiler comprising a curved shell having front and rear heads, atleast one of the heads being dished and having a fiat tube sheet portionand spherical marginal portions, the fiat tube sheet portion merginginto the spherical marginal portion laterally and below, said headhaving an intermediate portion above said tube sheet portion and betweenthe latter and the upper spherical marginal portion, said intermediateportion being substantially flat in a transverse direction and ofapproximately fiat curvature in vertical planes said substantially fiatportion being inclined at an acute angle to the plane of the tube sheetfor tensionally supporting the tube sheet portion and weight of thetubes, the opposite head having a flat tube sheet parallel to the tubesheet portion of the other head, and tubes of equal length bridging thetube sheets, the marginal portion of said head conforming to thecurvature of said shell and registering with the end edges of saidshell, said head being welded to said shell and said tubes being weldedto said tube sheet portion.

4. Boiler head comprising a dished member having a fiat tube sheetportion and a spherical marginal portion, the flat tube sheet portionmerging into the spherical marginal portion both laterally and below,said head having an intermediate portion above said tube sheet portion,between the latter and the upper spherical marginal portion, saidintermediate portion being substantially fiat in a transverse directionand of approximately fiat curvature in vertical planes saidsubstantially fiat portion being inclined at an acute angle to the planeof the tube sheet for tensionally supporting said tube sheet portion.

5. Boiler head comprising a-dished member having a flat tube sheetportion and. a spherical marginal portion, the fiat tube sheet portionmerging into the spherical marginal portion both laterally and below,said head having an intermediate portion above said tube sheet portionbetween the latter and the upper spherical marginal portion, saidintermediate portion being substantially fiat in a transverse directionand of approximately fiat curvature in vertical planes saidsubstantially flat portion being inclined at an acute angle to the planeof the tube sheet, for tensionally supporting said tube sheet portion,said head below said tube sheet portion being provided with a reentrantspherical depression bounding a manhead opening.

6. Boiler head comprising a dished member having a flat tube sheetportion and spherical marginal portions, the flat tube sheet portionmerging into the spherical marginal portion laterally and below, theperipheral edge portion of said head being cylindrical, the geometricalcylindrical elements of which edge portion being perpendicular to saidtube sheet portion, said head having an intermediate portion above saidtube sheet portion and between the latter and the upper sphericalmarginal portion, said intermediate portion being substantially fiat ina transverse direction and of approximately fiat curvature in verticalplanes said substantially flat portion being inclined at an acute angleto the plane of the tube sheet for tensionally supporting said tubesheet portion.

7. Boiler head asclaimed in claim 6, the cylindrical peripheral edgeportion being of progressively increasing length from the top to thebottom of said head.

PERCY JACKSON.

